The present invention relates to a seat belt reactor with a tensionless mechanism.
Published Japanese Patent Application No. 52-9891 discloses a seat belt reactor with a tensionless mechanism wherein an electric motor is operated right after a seat occupant has worn a seat belt so as to rotate a belt take-up shaft in a belt feeding direction by a predetermined angle, thereby to add a predetermined amount of slack to the seat belt. This known seat belt retractor, however, has a problem that since the predetermined amount of slack is added to the seat belt irrespective of the amount of an original slack which takes place when the occupant has worn the seat belt, the resultant amount of slack may exceed an allowable amount if the original slack is large. This may hamper the effective operation of the seat belt upon collision of a vehicle.
Another problem encountered in this known seat belt reactor resides in that since the belt take-up shaft is locked and prevented from rotating in the belt feeding direction, the belt cannot be pulled out of the seat belt retractor further once the tensionless state is established, thus restraining the seat occupant from changing his posture.